Thermostatic switch



' 1,612,958 1927 w. w. WILLIAMS v THERMOSTATI C SWITCH Filed June 7, 1923 2 Sheets-Sheet 1 Aiiokbe s.

Jan.

W. W. WILLIAMS THERMOSTATIG SWITCH Filed June 7. 1923 2 Sheets-Sheet 2 Patented Jan; 4, 1927.

I-TaoLsTjATss warms w. WILLIAMS, or atoommeron,ntmors'assmnoa T0 wrL'Lmms OIL-0- MATIC HEATINGCORPO BATION, OF BLOOIINGTON, ILLINOIS, A CORPORATION OF mammafiled June 7, 1923-. 1 Serial No. 643,843.

My invention relates to thermostatic swltches and more particularly to a controlmeans therefor. v

Y The object of my invention isin the provision of a thermal safety control mechanism for a fuel burning device. Another object of my invention is in the provision of a specially formed thermal metal control adapted to be used in a safety control unit for a fuel burnin device, said thermal metal control member 'ing specially formed to permit expansion of the thermal metal portion thereof to any degree without disturbance of the contact portions. Other objects of my invention will appear in the-following specification in connection with the annexed drawings inwhich, Figure 1 is a perspective of my thermal metal control member. Figure 2 is in a ing or box therefor. r

Figure 3 is a perspective of the contact portions 7 in connection with. the 7 thermal metal member.

Figure 4 is a side elevation, partially in section, of a fuel burning device showing its perspective of the coveradaptation to a furnace member and the location of my special thermal metal control.

Referring to the drawings, I have shown in Figure 4 an oil burning device which forms the subject matter of several co-pending applications, this device bein shown in its 0 rative position with 1818121011 to a formal drnace member.

Before describing my thermal metal control member, the novelty of which forms the basis of this application, I think itrnecessary to describe, although somewhat briefly,

' the operation of the formal fuel burning device'in connection with the operation of the safety control means therefor.

The fuel burning device shown in Figure 4 is adapted, by means of a series of pumps, to discharge an atomized fuel mixture into the furnace 10. An electric motor provides the power'means for the device and to permit automatic operation of the burner it is connected in an electrical circuit thru a series of switches with the formal thermostat,

located at somelconvenient point in r the 7 burning devices and is wellknown. the

art.'

There must necessarily be someignition means for the burner and although several well known means are used, I have utilized inthe present structure a combined gas and electric means which is controlled by the action of the burner-and which is described in .detail in my co pending application, No. 578,618.

The present application is directed to a specially formed thermal metal member adapted to beused in a safety control mechanism, for fuel burners. The art again shows several types of safety controls but the present one may be classified under the type, thermal safety controls, or in other words, the safety means for the fuel burning device, in case of non-ignition or failure of combustion, is'controlled by the heat or lack of heat within the combustion chamber.

As shown in Figure 1, my thermal control member is made up of a plate 11, which has integrally formed therewith an extended arm 12 which forms the lower half 13 ofa clamp member, the upper half of which is 'shown at 14. Screw members 15 and 16 provide the tightening means for said clamp. The above clamp surrounds preferably the fuel tube 17 and supports the thermal member adjacent the discharge opening and in close proximity'to the combustion chamber. Inserted, or rather positioned, in the plate 11 is an insulated contact point 18. A 7 spring bar 19 is attached to the plate 11 as at Y 20 and has thereon the second contact point 21. The spring bar 19 is attached to the plate ll normally, to prevent, due to its spring tension, the making of a contact between the points 18 and 21. .However, at

tached by the same means to the plate 11 is In view of the fact that my thermal con-' trol member is mounted within the draft tube of the'fueldevice, to permit a more sen sitive action thereof, a cover '23 surrounds the major port on-of the control and in such manner that the air blast thru the draft member will not be transmitted directly to the contact or thermal metal portions, and also the thermal metal strip is further covered by the flared portion 24, which is merely an extension of the top of the box. The box is open atone end, as clearly shown in Figure 1, to permit the thermal metal strip to protrude in a manner to be controlled by conditions within the combustion chamber.

An electrical connection is'shown at 25 between the insulated contact point 18 and a time switch which is in circuit with a series of relay switches, spark coils, etc.

In View of the fact that the time switch and other portions of the electrical circuit are not only well known in the art, but also, have been described in my'pending applications No. 552,816 and No. 501,618, I am confining my description merely to the portions which form the subject matter of the present application; in other. words, the thermal metal safety control member.

The operation of my thermal metal control member is as follows:

As said before, and as illustrated, the electrical connection 25 is in circuit with the formal time switch or heat coil and other electrical portions. Upon the initial movement of'the fuel burning device, the electrical circuit is completed and passes thru the contact points 18 and 21, which are in their normal or closed position. Normally the ignition means will almost immediately, or at least Very shortly, ignite the atomized fuel mixture which is now being discharged into the combustion chamber and there will be an immediate rise of temperature within said chamber. This rise in temperature in the combustion chamber acts immediately upon the sensitive thermal metal strip 22 and it will begin to extend with the result that the consequent release of the spring tension bar 19 will break the contact between the points -18 and 21, thus cutting out the time switch from the rest of the .electrical circuit and hence its operation.

The temperature may further increase within the combustion chamber with a still further extension of the thermal metal strip, but not with a further extension of the spring bar beyond its tensioned limit. The thermal metal strip is mounted in connection with the spring bar and cover in such manner that it may extend. due to heat action, outwardlyto any limit without coming in contact with the cover or flared portion 24:, thereof.

The structure of my thermal metal control member has been designed particularly to prevent abutment of this thermal metal strip with the housing or any other surface, and, as a matter of fact, the use of this thermal metal strip in connection with the tensioned spring bar has been developed to get away from the use of the thermal metal strip itself as a icontact member, because the extension of said thermal metal strip,

due to heat conditions, permits its striking at times against surfaces with the result that upon the cooling action it will not be capable of regaining its formal or normal posi tion.

Now we will say that the burner action ceases, whereupon cooling, or rather lowering of the temperature within the combustion chamber, permits the thermal metal strip to re-take its normal or cooled position; that is. abutting the upper side' of the spring bar and forcing the contact points'18 and 21 together, ready for the next successive movement of the burner.

I have described my thermal metal safety mechanism upon the normal operation of the burner. However, we will say that upon commencement of the burner, the ignition means fails and the atomized fuel is discharged, un-ignited, into the combustion chamber. In case this happens there is of course no rise in temperature within the combustion chamber, and hence no action of the thermal metal strip to release the spring bar which has the contact oint there on. In other words, the electrical contact is not broken thru the points 18 and 21, and consequently no cutting out of the time switch. This time switch has in connection therewith some means, usually a heat coil, for breaking the electrical connection to the fuel burner after a specified time, upon failure of ignition; and therefore, the nonrelease of the spring bar and contact points. After the limited time has elapsed the time switch will out out the electric motor and ering the contact portions. said housing having a flared cover portion, and a thermal metal strip attached to the plate and normally bearing upon the spring bar to make contact between the opposed points but adapted upon increased temperature conditions to release said spring bar and to'be extended without striking the housing memher.

In testimony whereof I afiix my signature.

WALTER W. \VILLIAMS. 

